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WO1980002418A1 - A method of purifying phosphoric acid of heavy metals - Google Patents

A method of purifying phosphoric acid of heavy metals Download PDF

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Publication number
WO1980002418A1
WO1980002418A1 PCT/SE1980/000134 SE8000134W WO8002418A1 WO 1980002418 A1 WO1980002418 A1 WO 1980002418A1 SE 8000134 W SE8000134 W SE 8000134W WO 8002418 A1 WO8002418 A1 WO 8002418A1
Authority
WO
WIPO (PCT)
Prior art keywords
phosphoric acid
heavy metals
sulphide
alkali
added
Prior art date
Application number
PCT/SE1980/000134
Other languages
English (en)
French (fr)
Inventor
H Berglund
Original Assignee
Boliden Ab
H Berglund
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Family has litigation
First worldwide family litigation filed litigation Critical https://patents.darts-ip.com/?family=20338025&utm_source=google_patent&utm_medium=platform_link&utm_campaign=public_patent_search&patent=WO1980002418(A1) "Global patent litigation dataset” by Darts-ip is licensed under a Creative Commons Attribution 4.0 International License.
Application filed by Boliden Ab, H Berglund filed Critical Boliden Ab
Publication of WO1980002418A1 publication Critical patent/WO1980002418A1/en
Priority to DK547780A priority Critical patent/DK151216C/da

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B25/00—Phosphorus; Compounds thereof
    • C01B25/16—Oxyacids of phosphorus; Salts thereof
    • C01B25/18—Phosphoric acid
    • C01B25/234—Purification; Stabilisation; Concentration
    • C01B25/237—Selective elimination of impurities
    • C01B25/238—Cationic impurities, e.g. arsenic compounds

Definitions

  • the present invention relates to a process for removing heavy metals, particularly cadmium, from differing qualities of wet-process phosphoric acids.
  • the invention is based on the concept of removing the heavy metals in sulfide form.
  • Phosphate raw materials contain varying quantities of heavy metals which, when digesting the phosphate raw material in acid, such as sulphuric acid, are dissolved and remain in the resultant phosphoric acid solution.
  • acid such as sulphuric acid
  • the heavy metals will be present in the end product.
  • Studies made in the agriculture industry on the problem of heavy metals over recent years have shown that more attention should be paid to the cadmium situation.
  • the bonds by which cadmium ions are bound to the ground are relatively weak and consequently cadmium can be readily taken up by plant growing in the ground and, in this way, passed to the nutrient chains via the ground, the animal food and the vegetables intended for human consumption.
  • the element cadmium is considered particularly dangerous, due to its long biological half life. It has been found that the long term exposure of cadmium to animals has, for example, resulted in proteinuri and kidney damage. Another known sickness promoted by cadmium is the so-called Itai-Itai-sickness in Japan, caused by the release of industrial cadmium and resulting in kidney damage and serious changes in bone structure. Thus, there are strong reasons to prevent, as far as possible, the entrance of cadmium into the various steps of the nutrient chain.
  • BPL Bone Phosphate Lime (% Ca 3 (PO 4 ) 2 )
  • Non-evaporated phosphoric acid, dihydrate process Non-evaporated phosphoric acid, dihydrate process.
  • Various methods of purifying phosphoric acid with respect to its heavy metal content are known to the art. Normally the various heavy metals, with the exception of cadmium, can be readily precipitated out and removed from the phosphoric acid, by, for example, adding hydrogen sulphide, sodium sulphide solution, potassium sulphide solution or an ammonium sulphide solution, or by adding calcium and barium sulphide. Cadmium is much more difficult to precipitate out than the other heavy metals mentioned.
  • the method requires a large surplus of sulphide in relation to the heavy metals, and, subsequent to filtering off the sulphides, results in the presence of hydrogen sulphide in the acid, which hydrogen sulphide must be removed.
  • the hydrogen sulphide can, for example, be driven off with air or removed by oxidation. This procedure is particularly disadvantageous in practice. From the aspect of working hygiene and from the point of view of the care and protection of the environment, the handling of hydrogen sulphide is a serious matter.
  • Another Japanese patent specification, No. 53075-196 proposes a method in which water-soluble metal sulphides are first pre-mixed with a calcium hydroxide suspension. This mixture is then added to the phosphoric acid, whereby cadmium sulphide, together with other heavy metals, are precipitated out and then separated.
  • the examples given illustrate that acceptable purification with regard to cadmium is obtained at molar ratios of Ca/SO 4 2- of 0.5; 1.0, and 1.5 and a molar ratio of S 2- /heavy metals greater than 10.
  • This latter methodology has been found applicable only to acids of particular composition. Thus, experiments show that the method cannot be used on wet-process phosphoric acid produced from the raw materials specified in Table 1 above.
  • the third method (German Offenlegungsschrift 2422902) is based on the concept of passing sulphuric acid under pressure (1-50 atm) down into the phosphoric acid and then removing the cadmium sulphide formed.
  • This method has the same disadvantage as the method disclosed in the aforementioned Japanese Patent Specification 7575-115.
  • the phosphoric acid was not satisfactorily purified of cadmium.
  • An object of the present invention is to provide a method by which wet-process phosphoric acid can be freed of heavy metals, particularly cadmium, irrespective of the phosphate raw material used in producing the phosphoric acid, and without needing to apply the difficult process steps associated with known techniques.
  • wet-process phosphoric acid produced by digesting raw phosphates with sulphuric acid always contains sulphuric acid residues.
  • the residual sulphuric acid present in the phosphoric acid is first removed, which can be effected, in principle, in two different ways, namely by neutralization with alkali or by precipitation as not-readily dissolved sulphate.
  • the phosphoric acid is admixed with alkali to an Me/P ratio within the range of about 0.05-0.3, preferably about 0.1-0.2; in which Me represents the number of cation equivalents in the alkaline solution used, while P represents the number of phosphorus atoms in the phosporic acid.
  • Me represents the number of cation equivalents in the alkaline solution used
  • P represents the number of phosphorus atoms in the phosporic acid.
  • the heavy metals are precipitated out in the phosphoric acid by adding thereto a sulphide compound which is soluble in the phosphoric acid and by then removing the resultant sulphide precipitant in a suitable manner.
  • the sulphide is suitably supplied in an excess quantity, the amount added preferably being selected so as to correspond to about 0.2-lg of S 2- per litre of phosphoric acid.
  • the alkali addition may conveniently be effected in two stages, whereat in the first stage a stoichiometric quantity of salt-forming cations corresponding to the residual sulphuric acid is added and the resultant sulphate separated out, while in the second stage further alkali is added to produce an Me/P ratio within said interval, or, alternatively, the alkali additon can be made in a single step while neutralizing the residual sulphuric acid to obtain the Me/P ratio.
  • a multiplicity of alkaline compounds such as ammonium hydroxide,sodium hydroxide or potassium hydroxide or mixtures thereof, can be used for neutralizing the sulphuric acid or for the addition of alkali. to obtain the desired Me/P ratio.
  • calcium hydroxide, calcium carbonate or calcium oxide, or a mixture thereof, can be used.
  • the kind of alkaline compound added is suitably selected with respect to the future use of the phosphoric acid.
  • the alkali added is suitably a calcium compound, for example one of those beforementioned.
  • the residual sulphuric acid present in the phosphoric acid is removed by precipitation of the not-readily dissolved sulphate
  • the precipitated sulphate can be removed in a suitable manner, for example by filtration.
  • Any suitable soluble sulphide compound can be used to precipitate out the heavy metals, .among them cadmium, present in phosphoric acid prepared in the afore described manner.
  • suitable sulphide compounds can be mentioned sodium sulphide, potassium sulphide, ammonium sulphide, calcium sulphide or hydrogen sulphide.
  • the phosphoric acid contains minor quantities of cadmium, e.g. about 10 tig per gram phosphoric acid and if the weight ratio of Cd:(As+Cu) is less than about 0.5 the precipitation of cadcan be facilitated by adding large excess quantities of the sulphide compound in relation to the heavy metals present. This is particularly the case when the Me/P molar ratio is less than about 0.1. In practice, it is suitable to add about twice the amount of sulphide compared with the afore mentioned normal quantity of about 0.2-lg of S 2- per litre of acid.
  • Example 10 is intended to illustrate the unsatisfactory purification of phosphoric acid with respect to cadmium obtained when applying the afore described known techniques.
  • Example No. 1 Example No. Example No. content 25 mg Cd/l 12 mg Cd/l 12 mg Cd/l one stage one stage two stages
  • Sulphate-purified phosphoric acid containing 45 % P 2 O 5 and, calculated per litre of acid, 16 mg As, 17 mg Cu and the following cadmium contents; 10, 20, 40 and 80 mg respectively, were neutralized to an Na:P ratio of 0.10 and admixed with 1 gram of commercially available Na 2 S per litre of phosphoric acid.
  • the heavy metal sulphides were filtered off after 2 hours. The results are given in Table 4.
  • a phosphoric acid which had been purified of sulphates and which had the same composition as that of Example 4 was purified of heavy metals in two stages, whereat arsenic sulphide and copper sulphide were precipitated out and filtered off in a first stage and cadmium sulphide was precipitated out in a second stage. It will be seen from
  • EXAMPLE 6 Phosphoric acids which had been purified of sulphate and which had varying P 2 O 5 concentrations were purified of heavy metals in a single stage in which the Na:P molar ratio was 0.10 and in which the temperature was 25 and 50°C respectively. In all cases the cadmium content of the phosphoric acids was 15 mg per 100 grams of P 2 O g or ⁇ 60 mg/l. In all cases the phosphoric acid was admixed with 1 gram of commercially available Na 2 S per litre, and after 2 hours the heavy metal sulphides were filtered off. The results are shown in Table 5 below.
  • Phosphoric acid which had been purified of sulphates and which contained 40 mg of Cd per litre was admixed with lime milk to a CaO:P 2 O 5 molar ratio of 0.20, whereafter the heavy metal sulphides were precipitated out in a single stage by adding 1 gram of commercially available Na 2 S per litre of acid.
  • the purified phosphoric acid contained 0.9 mg of Cd per litre.
  • the phosphoric acid had the following composition:
  • EXAMPLE 8 The phosphoric acid, purified of arsenic and partially purified of copper, was admixed with lime milk to obtain CaO:P 2 O 5 molar ratios of 0.10 0.20 and 0.30, and was admixed with varying quantities ofsodium sulphide, whereat the following results were obtained.
  • non-evaporated phosphoric acid having the following composition was purified of heavy metals: 31.4 % P 2 O 5
  • Ammonium hydroxide was added to 1000 ml of phosphoric acid in stoichiometric quantities relative to the content of sulphiric acid, whereafter further ammonium hydroxide was added to obtain an molar ratio of 0.25, whereafter 1.5 gram of Na 2 S was added as a 5 % solution. After 2 hours at ⁇ 60°C, the heavy-metal sulphide precipitate was filtered off.
  • Potassium hydroxide was added to 1000 ml of phosphoric acid in stoichiometric quantities relative to the sulphuric acid content, wherefurther potassium hydroxide was added to obtain a K 2 O/P 2 O 5 molar ratio of 0.25, whereafter 1.5g Na 2 S were added, as a 5 % solution. After 2 hours at ⁇ 60°C, the heavy-metal sulphides precipitated out were filtered off. The purified acid had the following heavy-metal content. 0.2 mg of As/l, 0.4 mg of Cu/l, 0.9 mg of Cd/l.

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Inorganic Chemistry (AREA)
  • Removal Of Specific Substances (AREA)
  • Solid-Sorbent Or Filter-Aiding Compositions (AREA)
  • Processing Of Solid Wastes (AREA)
  • Ultra Sonic Daignosis Equipment (AREA)
  • Medicines That Contain Protein Lipid Enzymes And Other Medicines (AREA)
PCT/SE1980/000134 1979-05-10 1980-05-08 A method of purifying phosphoric acid of heavy metals WO1980002418A1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
DK547780A DK151216C (da) 1979-05-10 1980-12-22 Fremgangsmaade til fjernelse af tunge metaller, isaer cadmium, fra phosphorsyre fremstillet ved den vaade metode

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
SE7904135 1979-05-10
SE7904135A SE418845B (sv) 1979-05-10 1979-05-10 Forfarande for rening av vatprocessfosforsyra

Publications (1)

Publication Number Publication Date
WO1980002418A1 true WO1980002418A1 (en) 1980-11-13

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Application Number Title Priority Date Filing Date
PCT/SE1980/000134 WO1980002418A1 (en) 1979-05-10 1980-05-08 A method of purifying phosphoric acid of heavy metals

Country Status (10)

Country Link
US (1) US4378340A (fi)
EP (1) EP0023195B2 (fi)
JP (1) JPH021086B2 (fi)
AT (1) ATE6050T1 (fi)
DE (1) DE3066353D1 (fi)
DK (1) DK151216C (fi)
FI (1) FI66162C (fi)
NO (1) NO152505C (fi)
SE (1) SE418845B (fi)
WO (1) WO1980002418A1 (fi)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2520342A1 (fr) * 1982-01-25 1983-07-29 Rhone Poulenc Chim Base Procede de purification d'acide phosphorique de voie humide
EP0253454A1 (en) * 1986-07-15 1988-01-20 Stamicarbon B.V. Process for the removal of heavy metals from acid, phosphate-containing aqueous media
EP0260616A2 (de) * 1986-09-13 1988-03-23 Chemische Fabrik Budenheim Rudolf A. Oetker Verfahren zur Behandlung von Nassverfahrensphosphorsäure
WO2009117583A3 (en) * 2008-03-20 2009-11-19 Sigma-Aldrich, Co Purification and preparation of phosphorus-containing compounds
FR3039830A1 (fr) * 2015-08-03 2017-02-10 Ocp Sa Procede de fabrication d'un engrais a base de phosphate d'ammonium presentant une teneur reduite en cadmium
EP4015452A1 (en) 2020-12-21 2022-06-22 Técnicas Reunidas, S.A. Process for producing technical grade phosphoric acid from sewage sludge ash

Families Citing this family (23)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3134847A1 (de) * 1981-09-03 1983-03-17 Hoechst Ag, 6000 Frankfurt "verfahren zur gewinnung cadmium-freier rohphosphorsaeure"
DE3202658A1 (de) * 1982-01-28 1983-08-04 Hoechst Ag, 6230 Frankfurt Verfahren zur entfernung von schwermetallionen aus nassverfahrensphosphorsaeure
EP0087065B1 (de) * 1982-02-12 1985-09-25 Hoechst Aktiengesellschaft Verfahren zur Verminderung des Schwermetallgehaltes im Rohphosphat
DE3218599A1 (de) * 1982-05-18 1983-12-01 Chemische Fabrik Budenheim Rudolf A. Oetker, 6501 Budenheim Verfahren zum entfernen von cadmium aus sauren, insbesondere p(pfeil abwaerts)2(pfeil abwaerts)0(pfeil abwaerts)5(pfeil abwaerts)-haltigen loesungen
DE3604483A1 (de) * 1986-02-13 1987-08-20 Hoechst Ag Verfahren zum entfernen von schwermetallen aus mineralsaeuren
DE3604920A1 (de) * 1986-02-17 1987-08-20 Hoechst Ag Verfahren zur herstellung von rohphosphorsaeure
DE3622597A1 (de) * 1986-07-04 1988-01-07 Budenheim Rud A Oetker Chemie Verfahren zur faellung und abtrennung von cadmiumsulfid aus den raffinaten der phosphorsaeurereinigung
NO164768C (no) * 1988-03-04 1990-11-14 Norsk Hydro As Fremgangsmaate for fjerning av tungmetaller, spesielt kadmium, fra fosforsyreholdige loesninger.
DE4327401A1 (de) * 1993-08-14 1995-02-16 Hoechst Ag Verfahren zur Entfernung von Blei und Cadmium aus Phosphorsäure
US20040179984A1 (en) * 2003-03-13 2004-09-16 Nagaraj D. R. Process for removing metal impurities from wet process phosphoric acid and compositions thereof
EA027805B1 (ru) * 2012-06-21 2017-09-29 Оутотек (Финлэнд) Ой Способ и установка для выделения тяжелых металлов из фосфорсодержащего исходного материала
DE102014006278B3 (de) 2014-05-02 2015-02-26 Remondis Aqua Gmbh & Co. Kg Verfahren zur Reinigung von Roh-Phosphorsäure (z.B. MGA-Säure) durch Zugabe von Aschen aus Abfall-Verbrennungsanlagen umfassend die Gewinnung von reiner Phosphorsäure, Kalziumsulfat, wasserlöslichen Kalziumhydrogenphosphaten und Metallsalz-Lösung
US10865110B2 (en) 2017-10-08 2020-12-15 Cytec Industries Inc. Compositions and processes for removing heavy metals from phosphoric acid solutions
EP3964478A1 (en) 2020-09-08 2022-03-09 Yara International ASA Process for the removal of heavy metals from a phosphoric acid containing composition
EP3964477A1 (en) 2020-09-08 2022-03-09 Yara International ASA Process for the removal of heavy metals from a phosphoric acid containing composition using an ionic polymeric surfactant
BR112022020189A2 (pt) 2020-06-16 2022-11-22 Yara Int Asa Processo para a remoção de metais pesados de uma composição contendo ácido fosfórico usando um agente de floculação
MA59953B1 (fr) 2020-06-16 2024-08-30 Yara International Asa Procédé d'élimination de métaux lourds d'une composition contenant de l'acide phosphorique à l'aide d'un tensioactif polymérique ionique et utilisation dudit tensioactif dans la précipitation de métaux lourds dans une composition contenant de l'acide phosphorique
EP4164815A1 (en) 2020-06-16 2023-04-19 Yara International ASA Process for the removal of heavy metals from a phosphoric acid containing composition
EP3964476A1 (en) 2020-09-08 2022-03-09 Yara International ASA Process for the removal of heavy metals from a phosphoric acid containing composition using a flocculating agent
AU2023332203A1 (en) 2022-09-02 2025-03-06 Cytec Industries Inc. Reagents and processes for removing heavy metals from phosphoric acid solutions
PL442462A1 (pl) * 2022-10-07 2024-04-08 Politechnika Wrocławska Sposób oczyszczania surowców fosforowych przez kalcynację z dodatkiem soli nieorganicznych
WO2024105263A1 (en) 2022-11-17 2024-05-23 Cytec Industries Inc. Compositions and processes for removing heavy metals from phosphoric acid containing streams
WO2024256668A1 (en) 2023-06-15 2024-12-19 Cytec Industries Inc. Heavy metals removal from phosphoric acid containing streams

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GB986154A (en) * 1961-04-20 1965-03-17 Progil Improvements in or relating to phosphoric acid purification
DE2429758A1 (de) * 1973-06-21 1975-01-23 Mitsubishi Chem Ind Verfahren zum reinigen nass aufgeschlossener phosphorsaeure
SE401668B (sv) * 1974-10-04 1978-05-22 Hoechst Ag Forfarande och anleggning for rening av ra, pa vata vegen framstelld fosforsyra

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JPS5375196A (en) * 1976-12-15 1978-07-04 Central Glass Co Ltd Removing method for heavy metals from phosphoric acid solution

Patent Citations (3)

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Publication number Priority date Publication date Assignee Title
GB986154A (en) * 1961-04-20 1965-03-17 Progil Improvements in or relating to phosphoric acid purification
DE2429758A1 (de) * 1973-06-21 1975-01-23 Mitsubishi Chem Ind Verfahren zum reinigen nass aufgeschlossener phosphorsaeure
SE401668B (sv) * 1974-10-04 1978-05-22 Hoechst Ag Forfarande och anleggning for rening av ra, pa vata vegen framstelld fosforsyra

Cited By (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2520342A1 (fr) * 1982-01-25 1983-07-29 Rhone Poulenc Chim Base Procede de purification d'acide phosphorique de voie humide
EP0253454A1 (en) * 1986-07-15 1988-01-20 Stamicarbon B.V. Process for the removal of heavy metals from acid, phosphate-containing aqueous media
US4822582A (en) * 1986-07-15 1989-04-18 Stamicarbon B.V. Process for the removal of heavy metals from acid, phosphate-containing, aqueous media
EP0260616A2 (de) * 1986-09-13 1988-03-23 Chemische Fabrik Budenheim Rudolf A. Oetker Verfahren zur Behandlung von Nassverfahrensphosphorsäure
EP0260616A3 (en) * 1986-09-13 1988-12-21 Chemische Fabrik Budenheim Rudolf A. Oetker Process for treating wet process phosphoric acid
CN101977920A (zh) * 2008-03-20 2011-02-16 西格玛-奥吉奇公司 含磷化合物的纯化和制备
WO2009117583A3 (en) * 2008-03-20 2009-11-19 Sigma-Aldrich, Co Purification and preparation of phosphorus-containing compounds
FR3039830A1 (fr) * 2015-08-03 2017-02-10 Ocp Sa Procede de fabrication d'un engrais a base de phosphate d'ammonium presentant une teneur reduite en cadmium
WO2017023153A3 (fr) * 2015-08-03 2017-03-30 Ocp Sa Procede de fabrication d'un engrais a base de phosphate d'ammonium presentant une teneur reduite en cadmium
CN109071368A (zh) * 2015-08-03 2018-12-21 Ocp有限公司 用于制备具有低镉含量的磷酸铵肥料的方法
EA035357B1 (ru) * 2015-08-03 2020-06-01 ОуСиПи СА Способ изготовления аммонийфосфатного удобрения с низким содержанием кадмия
AU2016303902B2 (en) * 2015-08-03 2021-03-04 Ocp Sa Method for manufacturing an ammonium phosphate fertilizer having low cadmium content
US10947164B2 (en) 2015-08-03 2021-03-16 Ocp Sa Method for manufacturing an ammonium phosphate fertilizer having low cadmium content
CN109071368B (zh) * 2015-08-03 2021-11-12 Ocp有限公司 用于制备具有低镉含量的磷酸铵肥料的方法
EP4015452A1 (en) 2020-12-21 2022-06-22 Técnicas Reunidas, S.A. Process for producing technical grade phosphoric acid from sewage sludge ash

Also Published As

Publication number Publication date
EP0023195A2 (en) 1981-01-28
EP0023195A3 (en) 1981-09-09
EP0023195B1 (en) 1984-02-01
SE7904135L (sv) 1980-11-11
NO152505C (no) 1985-10-09
FI801521A (fi) 1980-11-11
DK151216B (da) 1987-11-16
FI66162C (fi) 1984-09-10
DK151216C (da) 1988-07-18
EP0023195B2 (en) 1988-09-21
NO810039L (no) 1981-01-07
JPH021086B2 (fi) 1990-01-10
DE3066353D1 (en) 1984-03-08
DK547780A (da) 1980-12-22
FI66162B (fi) 1984-05-31
NO152505B (no) 1985-07-01
SE418845B (sv) 1981-06-29
JPS56500492A (fi) 1981-04-16
ATE6050T1 (de) 1984-02-15
US4378340A (en) 1983-03-29

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